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New Test May Predict Early Response to Chemotherapy

New Test May Predict Early Response to Chemotherapy

November 01, 2002

SAN FRANCISCOAn
investigational test kit (Apomate) to measure apoptosis may be able to detect a
positive or negative response to chemotherapy within just a few days of
initiation of treatment, allowing nonresponders to switch quickly to a
different treatment.

Neil D. Steinmetz, MD, vice president and medical director
of the Theseus Imaging division of North American Scientific, Inc., Boston, the
developer of Apomate, presented the study results at the 93rd Annual Meeting of
the American Association for Cancer Research (abstract 4136).

Apomate is a kit for the preparation of technetium
(Tc-99m)-labeled recombinant human annexin V, a 35-kD protein that binds to
phophatidyl-serine, which is expressed on the surface of cancer cells during
the early stages of apoptosis. Tc-99m releases a signal that can be visualized
using scintigraphic imaging. "Thus, the Apomate scan can be thought of as a
method that allows us to image dying cells in living patients," Dr. Steinmetz
said.

Apomate is administered via intravenous injection before
initiation of chemotherapy, and scintigrams are taken a few hours later to
determine baseline levels of spontaneous apoptosis. Apomate is again injected 1
to 3 days after the first chemotherapy dose. An increase in Apomate uptake
during the second scan, compared with baseline, is considered a positive
response. Study patients continue with their clinical treatment, and their
long-term response to chemotherapy is later compared with the results from
Apomate scintigraphy.

Preliminary phase I/II results obtained from patients
enrolled at centers in the United States and Europe have been positive, Dr.
Steinmetz said.

In one study of patients with non-small-cell lung cancer,
initial results were available from 13 patients enrolled at five centers. Five
patients had positive Apo-mate scans indicating increased apoptosis over
baseline. Of these five patients, three had responded to chemotherapy and two
had stable disease. Of the remaining eight patients who did not demonstrate a
positive Apomate response, six had either died or had progressive disease, and
two had stable disease.

In another study of 15 subjects with breast cancer, lung
cancer, or lymphoma, Apomate scan results were compared with outcomes up to 1
year after the initiation of chemotherapy. All seven of the patients who
responded to chemotherapy (three partial responses and four complete responses)
had a positive Apomate result. In contrast, none of the eight nonresponders had
a positive Apomate test, and six of these patients have died or experienced
progressive disease (P < .01).